۞ وَمَا كَانَ ٱلۡمُؤۡمِنُونَ لِيَنفِرُواْ كَآفَّةٗۚ فَلَوۡلَا نَفَرَ مِن كُلِّ فِرۡقَةٖ مِّنۡهُمۡ طَآئِفَةٞ لِّيَتَفَقَّهُواْ فِي ٱلدِّينِ وَلِيُنذِرُواْ قَوۡمَهُمۡ إِذَا رَجَعُوٓاْ إِلَيۡهِمۡ لَعَلَّهُمۡ يَحۡذَرُونَ

Wa maa kaanal mu'minoona liyanfiroo kaaaffah; falaw laa nafara min kulli firqatim minhum taaa'ifatul liyatafaqqahoo fiddeeni wa liyunziroo qawmahum izaa raja'ooo ilaihim la'allahum yahzaroon

Nor should the Believers all go forth together: if a contingent from every expedition remained behind, they could devote themselves to studies in religion, and admonish the people when they return to them,- that thus they (may learn) to guard themselves (against evil).

— At-Taubah (ٱلتَّوْبَة), 9:122